Riser on the Maersk Highlander
EXPLORATION • DRILLING • FIELD SERVICES
SECTION TITLE
One question did remain, however.
Tese vacant slots did not have all necessary lateral guide supports installed and therefore the conductor performance could be compromised. So, a means to provide this support had to be found. A retrospective installation of a lateral guide support below water level was deemed very risky, as it would involve divers. Initially, the client planned to install two supports: one above the water level and one below the water level. Tis is a hugely complicated job, particularly in a difficult North Sea environment. Aquaterra Energy’s integrated analysis and engineering team was brought in to show how this might be possible.
feasibility project on a platform in the Norwegian sector of the North Sea. Te installation had been active for around 15 years and the owner was looking to add two more conductors to enhance its production. With two available conductor slots, the solution seemed obvious – almost beyond question. Two conductors would be installed in the two spare slots, maximising the use of the pre-existing infrastructure.
Advanced analysis drives today’s optimisation
RELIABLE RESULTS Te analysts started by getting a comprehensive understanding of all the equipment within the plans and on site, including conductor design, water depths, environmental conditions, location of the guides and a variety of other different design specific parameters. Te information was then used to build a representative computer model in specialist software, allowing the team to simulate exactly how the system could react under many different conditions. One of the key factors to simulate was the North Sea conditions, as when a storm hits the waves can induce considerable load and movement on the conductors. Te loads were then read and compared to industry safety codes, which are set by API and DNV, allowing an accurate picture as to whether they were acceptable.
Not stopping there, the Aquaterra
Energy team took this a step further, looking at higher level models, varying ideas around how the support could be designed, where it could be placed and how it could be installed at a few different elevations. Ultimately, this was challenging the client’s idea to see if there were any better solutions available. With the analysis team being under the same roof as the offshore teams, it allowed potential solutions to be challenged on a feasibility basis, and therefore no solution was suggested that wasn’t possible to deliver.
MAJOR SAVINGS AND A NEW APPROACH Trough open dialogue and collaboration between the client and analysts, a rather welcome result awaited in the data. Te outcome of this assessment was significant, and saved the client over £4million in project costs and additional untold savings on future maintenance. How? Te analysis found a workable solution by only adding a support just above the water level. Tis was achieved by optimising the conductor pipe by increasing the wall thickness and designing out the need to install a support below the water level. Tis mitigated the need for an expensive second support and greatly simplified the planned operations. Notably, divers were no longer
required as the required support was above the water level, improving safety through reduced risk. As Aquaterra Energy works closely with its clients, the recommendation was made after liaising with the client to make sure it could obtain the required pipe size on time for the operations to begin. Providing independent advice, quickly, gave a fresh perspective for this type of project in future. In today’s environment, where safety, efficiency and enhanced production are close bedfellows, it has been all too easy for the industry to go with what’s been done before – but new and advanced analysis supports the drive to optimisation in the 21st century.
Dr AKM Eahsanul Haque is technical director of Dimension Strata www.dimension
strata.com
Martin Harrop is riser analysis manager at Aquaterra Energy.
www.aquaterraenergy.com
www.engineerlive.com 13
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